CHAPTER XII 



REPRODUCTION 



The organs concerned in reproduction are, in the 

 female, the ovary Avhich produces the egg or cell from 

 which the new being is to be formed, the fallopian tube, 

 which conveys the egg to the uterus, which is the hatch- 

 ing apparatus, and the vagina through which the egg 

 is fertilized and the child born. 



Menstruation is seen in the female only. It begins 

 usually in the fourteenth or fifteenth year and recurs 

 at intervals of about 28 days until the "change of life," 

 climacteric, or menopause, which occurs between the 

 forty-fifth and fiftieth years. The appearance of the 

 menstrual flow is earlier in warm than in cold climates; 

 and the cessation of the function varies greatly in dif- 

 ferent individuals. Removal of the ovaries causes an 

 artificial menopause. It is clear, then, that the activity 

 of the ovary is periodic and is responsible for menstru- 

 ation; but the actual flow of blood is a function of the 

 uterus, probably in preparation for the reception of the 

 fertile egg. The lining (mucous) membrane of the 

 uterus thickens and becomes engorged with blood four 

 or five days before the appearance of the flow. There 

 follows a period, usually of four days, in which there is 

 hemorrhage into the uterus and the swollen membrane 

 is cast off and this is followed by about a week of re- 

 generation during which time the membrane returns to 

 its normal condition. The next twelve days constitute 

 the resting period. 



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